Interferon acts to mediate natural immunity to protect against viral infection and to initiate inflammatory reactions that protect against bacterial infections. Interferon has also been shown to be an effective anti-tumor or anticancer agent.
Previously, the administration of interferon has often required frequent subcutaneous injections, given at intervals which resulted in fluctuating medication levels. However, many conditions treated by interferon therapy may respond better to controlled levels of interferon which may provide more effective prophylactic or therapeutic effects.
Attempts to control and sustain medication levels in humans or animals between the administration of doses have more recently included the use of biodegradable polymers as matrices for controlling the release of medicaments. In some cases, biodegradable polymers, under in vivo conditions, exhibited high initial bursts of medicament release and minimal release thereafter.
Furthermore, methods used to form controlled release compositions have often resulted in a loss of activity of the medicament due to the instability of the medicament, chemical interactions between the medicament and the other components contained in, or used in formulating, the controlled release composition, or have resulted in losses of medicament due to the formulation process.
Therefore, a need exists for a means of controlling the release of interferon while not inordinately reducing the activity, or potency, of the interferon released.
This invention relates to a composition, and method of forming said composition, for the controlled release of interferon. The controlled release composition of this invention comprises a biocompatible polymer and particles of metal cation-stabilized interferon, wherein the particles are dispersed within the biocompatible polymer.
The method of the invention, for producing a composition for the controlled release of interferon, includes dissolving a polymer in a polymer solvent to form a polymer solution, dispersing particles of metal cation-stabilized interferon in the polymer solution, and then solidifying the polymer to form a polymeric matrix containing a dispersion of the metal cation-stabilized interferon particles.
The advantages of a controlled release formulation for interferon include increased patient compliance and acceptance by reducing the number of subcutaneous injections, increased therapeutic benefit by eliminating fluctuations in interferon concentration in blood levels, and potentially lowering the total administered amount of interferon by reducing these fluctuations. The advantages further include a reduction of the loss of the interferon""s biological activity which allows for the use of a lower amount of interferon to form a controlled release composition.